CBSE Class 10 Science Ch-3 Metals And Non-Metals Notes

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CBSE Class 10 Science Ch-3 Metals And Non-Metals
CBSE Class 10 Science Ch-3 Metals And Non-Metals

CBSE Class 10 Science Ch-3 Metals And Non-Metals Notes

Hello Students, here we are uploading the important notes of CBSE Class 10 Science Chapter 3 Metals and Non-Metals.

This is going to be very crucial for your board exams as this includes frequently asked most important questions of Science Chapter 3 i.e. metals and non metals.

While doing so we have gone through different text book keeping in center the NCERT text book of Science.

We have also gone through the important questions asked in the board exams of previous years.

We have taken some of the facts from various sources like kvs student support materials and various unsolved questions. I hope these important notes will prove beneficial for you.

CHAPTER 3- METALS AND NON-METALS

 

INTRODUCTION

Elements can be classified as metals and non-metals on the basis of their properties.

  • Example of some metals are :

Iron (Fe), Aluminium (Al), Silver (Ag), Copper (Cu)

  • Examples of some non-metals are :

Hydrogen (H), Nitrogen (N), Sulphur (S), Oxygen (O)

Property Metals Non-Metals
1. Lustre Metals have shining surface. They do not have

shining surface.

• Except Iodine.

2. Hardness They are generally hard.

• Except Sodium, Lithium and

Potassium which are soft and can

be cut with knife.

Generally soft.

• Except Diamond, a

form of carbon which

is the hardest natural

substance.

3. State Exist as solids.

• Except Mercury.

Exist as solids or

gaseous.

• Except Bromine.

4. Malleability Metals can be beaten into thin sheets.

• Gold and Silver are the most

malleable metals.

Non-metals are non-malleable.
5. Ductility Metals can be drawn into thin wires. They are non-ductile.
6. Conductor

of heat & electricity

Metals are good conductors of heat

and electricity.

• Silver (Ag) and Copper (Cu) : Best conductors of heat.

• Lead (Pb), Mercury (Hg) poor conductor of heat.

Non-metals are poor

conductor of heat and

electricity.

• Except Graphite.

7. Density Generally have high density and high melting point.

• Except Sodium and Potassium.

Have low density and

low melting point.

8. Sonorous Metals produce a sound on striking a hard surface. They are not sonorous.
9. Oxides Metallic oxides are basic in nature. Non-metallic oxides

are acidic in nature.

 

 

CHEMICAL PROPERTIES OF METALS 

(A) Reaction with Air :

Metals combine with oxygen to form metal oxide.

Metal + O2 Metal oxide

Examples :

(i) 2Cu                    +                  O2           →              2CuO

Copper oxide (black)

(ii) 4Al                   +                  3O2         →              2Al2O3

Aluminium oxide

(iii) 2Mg                +                   O2          →              2MgO

Different metals show different reactivities towards O2.

  • Na and K react so vigorously that they catch fire if kept in open so they are kept immersed in kerosene.
  • Surfaces of Mg, Al, Zn, Pb are covered with a thin layer of oxide which prevent them from further oxidation.
  • Fe does not burn on heating but iron fillings burn vigorously.
  • Cu does not burn but is coated with black copper oxide.
  • Au and Ag does not react with oxygen.

 

Amphoteric Oxides : Metal oxides which react with both acids as well as bases to produce salts and water are called amphoteric oxides.

Examples : Al2O3 + 6HCl → 2AlCl3 + H2O

Al2O3 + 2NaOH → 2NaAlO2 + H2O

Sodium

Aluminate

 

(B) Reaction of Metals with Water :

Metal + Water → Metal oxide + Hydrogen

Metal oxide + Water → Metal hydroxide

Examples :

(i) 2Na + 2H2O → 2NaOH + H2 + Heat

(ii) Ca + 2H2O → Ca(OH) 2 + H2

(iii)Mg + 2H2O → Mg(OH)2 + H2

(iv) 2Al + 3H2O → Al2O3 + 3H2

(v) 3Fe + 4H2O → Fe3O4 + 4H2

 

(C) Reaction of Metals with Acids (Dilute) :

Metal + Dilute acid → Salt + H2

Cu, Ag, Hg do not react with dil. acids.

Examples :

(i) Fe + 2HCl → FeCl2 + H2

(ii) Mg + 2HCl → MgCl2 + H2

(iii)Zn + 2HCl → ZnCl2 + H2

(iv) 2Al + 6HCl → 2AlCl3 + 3H2

 

 (D) Reaction of Metals with Solutions of other Metal Salts :

Metal A + Salt solution B → Salt solution A + Metal B

  • Reactive metals can displace less reactive metals from their compounds in solution form.

Fe + CuSO4 FeSO4 + Cu

 

REACTIVITY SERIES

The reactivity series is a list of metals arranged in the order of their decreasing activities.


K                                             Most reactive 

Na

Ca

Mg

Al

Zn                                            Reactivity decreases

Fe

Pb

H

Cu

Hg

Ag

Au                                           Least reactive


Reaction of Metals with Non-metals

  • Reactivity of elements is the tendency to attain a completely filled valence shell.
  • Atoms of the metals lose electrons from their valence shell to form cation.

Atom of the non-metals gain electrons in the valence shell to form anion.

E.g., Formation of NaCl

Na                   →                   Na+       +         e

2, 8, 1                                     2, 8

Sodium cation

 

Cl                    +          e        →                    Cl

2, 8, 7                                                             2, 8, 8

Chloride anion

Ionic Compounds

The compounds formed by the transfer of electrons from a metal to a non-metal are called ionic compounds or electrovalent compounds.

Properties of Ionic Compounds 

  1. Physical nature : The are solid and hard, generally brittle.
  2. Melting and Boiling Point : They have high melting and boiling point.
  3. Solubility : Generally soluble in water and insoluble in solvents such as kerosene, petrol etc.
  1. Conduction of electricity : Ionic compounds conduct electricity in molten and solution form but not in solid state. 

Occurrence of Metals

 

Minerals : The elements or compounds which occur naturally in the earth’s crust are called minerals.

Ores : Minerals that contain very high percentage of particular metal and the metal can be profitably extracted from it, such minerals are called ores.

Tendency Metals Extraction Method
Very reactive metals K

Na

Ca

Mg

Al

Not found in free state

 

Extraction by electrolysis

Moderately reactive Zn

Fe

Pb

Cu

Hg

Occur as sulphides, oxides, carbonates

 

Reduction by using carbon

Least reactive Ag

Au

Occur in native/free state

 

Some Important Terms

(a) Gangue : Ores are usually contaminated with large amount of impurities such as soil, sand etc. called gangue. 

(b) Roasting : The sulphide ores are converted into oxides by heating strongly in the presence of excess air. This process is called roasting.

2ZnS + 3O2                                     2ZnO + 2SO2

                                                HEAT

 

(c) Calcination : The carbonate ores are changed into oxides by heating strongly in limited air. This process is called calcination.

 

ZnCO3                                    ZnO + CO2

                                HEAT

 (d) Reduction : Metal oxides are reduced to corresponding metals by using reducing agent like carbon.

ZnO + C → Zn + CO

Refining of Metals

The most widely used method for refining impure metal is electrolytic refining.

Refining of Metals
Refining of Metals
  • Anode : Impure copper
  • Cathode : Strip of pure copper
  • Electrolyte : Solution of acidified copper sulphate

(a) On passing the current through electrolyte, the impure metal from anode dissolves into the electrolyte.

(b) An equivalent amount of pure metal from the electrolyte is deposited at the cathode.

(c) The insoluble impurities settle down at the bottom of the anode and is called anode mud.

Corrosion

The surface of some metals such as iron is corroded when they are exposed to moist air for a long period of time. This is called corrosion.

(i) Silver becomes black when exposed to air as it reacts with air to form a coating of silver sulphide.

(ii) Copper reacts with moist carbon dioxide in the air and gains a green coat of copper carbonate.

(iii) Iron when exposed to moist air acquires a coating of a brown flaky substance called rust.

Prevention of Corrosion

The rusting of iron can be prevented by painting, oiling, greasing, galvanizing, chrome plating, anodizing or making alloys.

Galvanization : It is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc.

Alloy : An alloy is a homogenous mixture of two or more metals or a meta and a non-metal.

Iron : Mixed with small amount of carbon becomes hard and strong.

Steel : Iron + Nickel and chromium

Brass : Copper + Zinc

Bronze : Copper + Tin (Sn)

Solder : Lead + tin

Amalgam : If one of the metal is mercury (Hg).

 

IMPORTANT AND FREQUENTLY ASKED VERY SHORT QUESTIONS (1 Mark)
  1. Name one lustrous non-metal.
  2. Name two metals that are soft and can be cut with a knife.
  3. Number of electrons gained or lost by an element is called its…………….. .
  4. What are minerals?
  5. What is the process of depositing zinc on iron called?
  6. Which metal do not react with water at all?
  7. Name the ion made by non-metals – cation/anion.
  8. Bronze is an alloy made by the combination of…………..and………….. .
  9. Name two metals that are stored in kerosene oil.
  10. Arrange copper, silver and aluminium in increasing order of reactivity.
IMPORTANT AND FREQUENTLY ASKED SHORT ANSWER TYPE QUESTIONS (2 Marks)
  1. Give reasons :

(a) Why is pure gold not suitable for making ornaments?

(b) Why calcium is found in the form of compound?

(c) Why electrical wires are coated with PVC (Poly Vinyl Chloride)?

(d) Why do we apply oil on iron tools kept in storage?

(e) Why sodium is stored in kerosene oil?

IMPORTANT AND FREQUENTLY ASKED SHORT ANSWER TYPE QUESTIONS (3 Marks)
  1. Why Caesium and gallium melt in our palm?
  2. Why magnesium ribbon starts floating in hot water?
  3. What are ionic compounds?
  4. Complete the following chemical reactions :

(a) 3Fe + 4H2O →

(b) Ca + H2O →

(c) K + H2O →

  1. To obtain metal from their metal oxide, which chemical process is used? Give the chemical equation as well.
IMPORTANT AND FREQUENTLY ASKED LONG ANSWER TYPE QUESTIONS (5 Marks)
  1. What is the difference between a mineral and an ore?
  2. Differentiate between roasting and calcinations process in metallurgy.
  3. What is an alloy? Name the alloy which has iron, nickel and chromium as its constituents. What is the chief use of this alloy?
  4. Explain any two ways to prevent rusting of iron.
  5. Explain briefly electrolytic refining method.

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